3rd Generation Partnership Project (3GPP) defines the use of an Emergency Setup message in 3G mode when a mobile station (UE) transmits an emergency call to a police department, afire department, an emergency medical service, or the like (see Non-patent document 1, for example).
The Emergency Setup message does not define an information element (IE) that indicates a telephone number of a called party (a calling number). Here, an Emergency Category (such as fire or ambulance) linked with the calling number (such as 119) is selected and the Emergency Setup message including the Emergency Category is transmitted from the mobile station to an MSC (Mobile services Switching Center, which is a call control device). Note that the above-described method of processing an emergency call also applies to Long Term Evolution (LTE) mode although LTE uses an INVITE message in accordance with the Session Initial Protocol (SIP) instead of the Emergency Setup message.
In the meantime, from the viewpoint of personal information protection, communication common carriers are obligated to allow a calling party of such an emergency call to choose whether or not to notify a called party, i.e., a Public Safety Answering Point (PSAP, or an emergency call answering point), of a telephone number of the calling party (see http://www.soumu.go.jp/main_sosiki/joho_tsusin/d_syohi/tele com_perinfo_guideline_intro.html, for example).
For this reason, the calling number with the addition of a prefix (184 in Japan, for example), which indicates whether or not to notify the called party of the telephone number of the calling party, may be inputted as calling number information (such as 184119) to the mobile station by the calling party. As mentioned above, the Emergency Setup message (or the INVITE message) is not usable to notify the call control device of the above-mentioned calling number information with the addition of the prefix. Accordingly, when the above-mentioned calling number information is inputted, the mobile station notifies the call control device of the calling number information by treating the call as a general call instead of the emergency call. Thus, the mobile station controls notification of the telephone number of the calling party to the called party.